Measurement of dietary intake is a central component of nutrition research. However, a variety of measurement errors in virtually all methods of dietary assessment suggest a cautious interpretation of dietary data. The sources of error may be systematic or random. There has been increasing recognition of underreporting of food intake in dietary surveys as a source of measurement error. Dietary intakes obtained from all self-reported methods of dietary assessment--24-hour recalls, records, history, and food frequency questionnaires--have been shown to be underestimates of energy intake. Limited information on who is more likely to underreport is also available. For example, women and overweight individuals were more likely to underreport food intake in some studies. However, little is known about what is underreported. Because underreporting of food intake can bias results of studies focusing on diet and disease relationships, it is an important area of investigation. The purpose of this small grant proposal is to examine nationally representative data to determine the nature of underreporting. The study will use dietary data from the third National Health and Nutrition Examination Survey (NHANES III), 1988-1994 (n=15,979), to determine what is underreported. The specific aims of this study are to determine whether food group intake or eating behaviors of dietary underreporters differ from those of adequate reporters. The significance of the proposed research is that findings of this study will help in: 1) strategies for improving dietary assessment methods, and 2) interpretation of results from analytic epidemiology studies relating food intake to disease by providing information on what kinds of foods are likely to be underreported.